Sensei serves as the sole human instructor at Seishou Academy, where students embody personified firearms. He acts as homeroom teacher for the assault rifle class, overseeing anthropomorphized weapons including Funco (FN FNC), Ichiroku (M16A4), Elle (L85A1), and Sig (SG 550). His responsibilities involve educating and managing these students while navigating their unique behaviors and traits linked to real-world firearm characteristics.

Funco maintains unreciprocated romantic feelings toward him, generating comedic or awkward encounters. One incident sees him accidentally provoke Funco by referencing her skeleton stock—visually represented as a thong—resulting in her firing live ammunition at him. Though well-intentioned, Sensei occasionally misjudges the students' sensitivities regarding their firearm attributes.

During a critical battle against rival institution Akaganekou (Red Steel High), he sustains gunshot injuries. This contrasts his human vulnerability—evidenced by visible bleeding—with the weapon-girls' resilience. Funco subsequently claims their bullets cannot kill humans, though the narrative refrains from confirming this assertion. His full name remains undisclosed; he is exclusively addressed as "Sensei" or "Japanese Teacher" by students and staff.